Strained Ionic Interfaces: Effect on Oxygen Diffusivity from Atomistic Simulations

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• 作者：Dilpuneet S. Aidhy ; Yanwen Zhang ; William J. Weber
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：February 27, 2014
• 年：2014
• 卷：118
• 期：8
• 页码：4207-4212
• 全文大小：365K
• 年卷期：v.118,no.8(February 27, 2014)
• ISSN：1932-7455

文摘

The role of materials鈥?interfaces/grain boundaries on enhancing anion conductivity is an intensely debated issue that has exposed limited understanding on point-defect energetics at interfaces. Using static atomistic simulations on ZrO₂ | CeO₂ and ThO₂ | CeO₂ interfaces, we disentangle key interface issues, i.e., oxygen vacancy migration barriers at interfaces in the absence and presence of dopants, and oxygen vacancy-dopant binding energies at interfaces. The results show that, while pure, strained interfaces indeed possess very low oxygen migration barriers, the segregated dopants counteract and significantly raise the barriers. In addition, the dopants bind oxygen vacancies much more strongly at the interfaces than in the bulk, thereby further lowering oxygen diffusivity at interfaces. From our simulations, we conclude that the concept of strained interfaces to enhance anion conductivity prevails primarily in the absence of segregated dopants, and strategies that prevent dopant segregation need to be considered in the design of anion-conducting interfacial materials.